The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
Operation of the pneumatic brake system on railroad cars and certain types of trucks employ flexible air hoses extending between separate railroad cars or between the truck tractor and the trailer. Outer ends of the flexible air hoses are terminated with mating coupling members enabling ease of hose attachment and detachment. One of these couplings, commonly known as a glad hand coupling, is widely used in such applications. Such glad hand couplings are designed and manufactured to meet various standards and, in particular, to meet the standards of Association of American Railroads, so as to ensure ease of interchangeability between various manufacturers.
For connecting opposite ends of the air hoses in an air tight manner, these air brake hose couplings are joined by a rotational movement enabling engagement of mating lugs and flanges extending from each coupling body and forming an air tight passage between two air hoses. As it well known, in applications for railroad cars, such connection is located between the opposed ends of two coupled railroad cars and is also located in close proximity to the ground surface as each hose is suspended by an adjustable hose support which is attached to the air brake hose coupling at one end and to a respective railroad car coupler at a distal end. The, hose support must be adjusted for each individual air brake hose coupling connection to maintain a predetermined clearance with the ground surface.
In operation, the air pressure communicated through the connected air lines maintains air brakes of the individual railroad cars in the released position with any loss of the air pressure resulting in a brake application and, more importantly, if unintended may result in unwanted and undesired stopping of the entire train consist.
If the hose support adjustment has not been properly executed, it will result in the air brake hose coupling connection being disposed too close to the ground surface which is subject to premature uncoupling when struck by a raised object, for example a grade crossing or the like, lying between the tracks. Such premature uncoupling results in previously described undesired emergency braking.
To prevent unwanted braking, locking devices of various types have been employed to prevent separation of the air brake hose coupling.
U.S. Pat. No. 5,971,442 to Kozinski et al; U.S. Pat. Nos. 5,388,864 and 3,879,066, both to Kozinski disclose a flange protruding outwardly and forwardly from a rear portion of a housing and is provided with a lip engaging a similar lip formed on the arcuate locking lug of the other housing.
U.S. Pat. No. 5,911,444 to Buchter et al teaches a stop assembly having a spring loaded pin disposed within a bore of a first coupling housing. Pressurization of the brake system causes movement of the stop assembly to obstruct a path of the mating coupling housing thereby preventing rotational uncoupling of the housings.
U.S. Pat. No. 3,892,431 to Booth; and U.S. Pat. No. 1,354,643 to Brower disclose a spring loaded pin being disposed within a bore of a coupling housing and engaging either a hole, slot or a socket.
Such prior art designs require complete replacement of the installed air brake hose coupling with a new type design thus substantially increasing the costs of providing anti-rotational capability.
U.S. Pat. No. 6,669,237 to Burch et al teaches a pivotally mounted pawl mounted to one coupling member and having a ramp for engaging the other coupling member.
U.S. Pat. No. 5,685,573 to Nadherny et al discloses a band assembly having a strap attached to an air hose and oriented in a predetermined relationship to the first air brake hose coupling and an anti-rotational wire attached to the strap at one end and having a second end engaging the lip of a mating air brake hose coupling to prevent rotational uncoupling.
U.S. Pat. No 5,251,666 to Kimball et al discloses a fork like locking member mounted to reciprocate on the coupling body adjacent one of the flanges between release and engaged positions and a leaf spring urging such locking member into the engage position to prevent passage of a corresponding flange of the other coupling body.
U.S. Pat. No 4,747,623 to Newcomb et al teaches an attachment secured to one part of the air brake hose coupling which includes a rigid blocking member having a yoke and a blocking pin installed through such yoke and being held with a releasable wire bail or tether. The blocking pin prevents rotation of the coupling section.
Such prior art designs require costly field modifications of the existing air brake hose couplings.
Therefore, there is a need for a simple and reliable locking device for a pair of mating air brake hose couplings which can be easily installed without the need for special tools or modifications of the existing couplings.